MSTest exception: Unit Test Adapter threw exception: Type is not resolved for member

In my project I write tests using Microsoft's unit testing framework. All of my tests pass when I run them from Visual Studio but when I run the tests from MSBuild all of the tests fail with the following erorr message:

Unit Test Adapter threw exception: Type is not resolved for member SomeType,SomeAssembly Version=assemblyVersion, Culture=neutral, PublicKeyToken=..

The assembly not found is a 3rd party assembly referenced by all of the projects.

The build script is used by TFS so I've aded the following lines:

<RunTest>true</RunTest>

<ItemGroup>
    <MetaDataFile Include="$(BuildProjectFolderPath)myproject.vsmdi">
        <TestList>CI_Tests</TestList>
    </MetaDataFile>
</ItemGroup>

I've found the this post that shows a solution to this issue but unfortunatly I cannot chnage the files on the TFS server.

Help!

Solution

The first thing to check would be if this assembly is copied to the folder from which msbuild runs the tests. It might be the case that you have a copy in your bin/Debug folder because of some historic reasons, but the dependency is not set up properly in the project.